In order to keep the competitiveness of the third generation mobile communication system in the communication field, the 3rd Generation Partnership Project (3GPP) standard work group is devoted to the research of the Evolved Packet System (EPS). The whole EPS system mainly includes two parts, the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and the Evolved Packet Core (EPC). The EPC of that system can support the user's accessing from the global mobile communication system (GSM)/enhanced data rate GSM service (EDGE) radio access network (GERAN) and the Universal Terrestrial Radio Access Network (UTRAN).
The EPC packet core network includes the Home Subscriber Server (HSS), the Mobility Management Entity (MME), the Serving Gateway (S-GW), the packet data network (PDN) gateway (P-GW), the Serving GPRS Support Node (SGSN) and the Policy and Charging Enforcement Function (PCRF), wherein:
the HSS is the permanent storage place of the subscription data of the users, located in the home network where the users sign the contract;
the MME is the storage place of the subscription data of the users in the current network, responsible for the management of signaling from the terminal to the network Non-Access Stratum (NAS), the tracing and paging management function of the user in the idle mode, and the bearing management;
the S-GW is the gateway from the core network to the wireless system, responsible for the user plane bearing from the terminal to the core network, the data buffer of the terminal under the idle mode, the function of initiating the service request by the network side, the legal eavesdropping, and the packet data routing and forwarding function;
the P-GW is a gateway of an evolved packet domain system (EPS) and an outside network of that system, responsible for the functions, such as, the terminal IP address allocation, the charging function, the packet filtering, the policy application, etc.;
the SGSN is a service support point of accessing the EPC network by the GERAN and UTRAN users, similar to the MME functionally, responsible for the functions, such as, the update of the user location, the paging management and the bearing management, etc.; and
the PCRF is responsible for providing the policy control and charging for the PCEF.
Under some scenes, in order to expand the wireless coverage range, or increase the ability of wirelessly providing the access users temporarily, the concept of the Relay Node is introduced. The schematic diagram of the network framework is shown in FIG. 1, and the network element is explained as follows.
The Relay Node (RN) includes two parts of functions, the UE and the relay node. The RN, on one hand, acts as the UE to access the network, performing related operations such as establishing the bear, and on the other hand, as the eNB to provide access for the UE.
The donor eNodeB (Donor eNodeB, DeNB) provides the wireless access for the RN, terminates the wireless resource control (RRC) signaling of the RN-UE, and terminates the S1AP signaling and the X2 signaling of the RN-eNB. And also it is built in with the SGW and the PGW of the RN-UE at the same time.
The Relay Node Operator and Management (RN OAM) is used for the RN to obtain essential connection information therefrom.
The main purpose for the operator to deploy the framework is to expand the coverage range of the eNodeB through deploying the relay node at some places where it is inconvenient to deploy the wired connection, such as, relatively remote under-developed area, or sudden large-scale meeting or match. And under this kind of scene, the position of the relay node is generally fixed. However, with the application of the relay node, the operator begins to consider applying this technology to more extensive scene, for example, on the high-speed railway. Because the train is moving at a high speed, a large number of wired commercial facilities are required to deploy along the line of the train, this has increased the deployment cost of the operator greatly; while the wireless link between the relay node and the donor eNodeB can just reduce the cost, therefore, it is favored by the operator, and this kind of device is called the mobile relay (MR), which can be referred to FIG. 2.
Because the current DeNB serving cell can be the long term evolution frequency division duplex (LTE-FDD) cell and also can be the long term evolution time division duplex (LTE-TDD) cell. In the LTE-TDD system, because it adopts the time division duplex mechanism, the proportion of the uplink and downlink subframes can be configured in a flexible way. There are 10 subframes existed in the frame structure of the LTE-TDD system, and the subframe is divided into two types, the regular subframe and the special subframe; the regular subframe is formed by two time slots with length of 0.5 ms, and the special subframe is formed by three special time slots, which are respectively the downlink pilot frequency time slot, the uplink pilot frequency time slot and the guard space, and the sum of the lengths of these three special time slots is 1 ms. The LTE-TDD system has 9 kinds of different special subframe configuration modes. The LTE-TDD subframe configuration information carried in the serving cell currently is shown in Table 1. When the MR moves over into the next DeNB, the target DeNB cell needs to set the TDD configuration (TDD-config) according to the proportion of the uplink and downlink flowrates (traffics) of the MR, or continuously uses the TDD subframe configuration of the current serving DeNB cell. Especially, the current LTE-TDD cell can dynamically adjust the TDD subframe configuration according to the service condition of the current cell, that is, the TDD subframe configuration of the next DeNB serving cell, to which the current DeNB serving cell and the MR move over, is preferably able to keep the continuity. However, it is a problem to be solved how the target DeNB cell guarantees to be able to perform the TDD subframe configuration effectively and fast when the mobile relay node moves among multiple donor eNodeBs at present.
TABLE 1LTE-TDD subframe configuration informationRegular subframeENUMERATED (sa0, sa1, sa2, sa3, sa4, sa5,configurationsa6, . . . )Special subframeconfiguration>Special subframe modeENUMERATED(ssp0, ssp1, ssp2, ssp3, ssp4,ssp5, ssp6, ssp7, ssp8, . . . )>Downlink cycle prefixENUMERATED(Normal, Extended, . . . )>Uplink cycle prefixENUMERATED(Normal, Extended, . . . )